Zinc alloys



Patented Sept. 15, 1936 UNITED-STATES ZINC ALLOYS Leland E. Wemple, Chicago, Ill., and John R.

Daesen, Wilkes-Barre, Pa.

No Drawing. Application January 20, 1931, Serial No. 510,059

2 Claims.

Our invention relates to new and useful alloys of zinc whose advantages will be hereinafter set forth. The alloys are prepared by adding to 100 parts of zinc from to 2% parts of metallic copper and from 1/100 to part of chromium. The alloys should be free from aluminum or mag.- nesium, preferably completely, but in any event in proportion so substantial as to aflect adversely their valuable characteristics hereinafter de- 1 scribed.

The use of zinc, particularly when rolled into the form of sheets or strips, is limited because of its low tensile strength, its slight hardness, and the rapid dulling of its surface. These disadvantages are overcome if there be added to the zinc copperin the proportion of 1% to 2 parts, but preferably to 2 parts, and chromium (hereinafter referred to as third' metal), preferably from 1% to part, although where the alloys are to meet a high load strain up to part of the third metal may be used. Alloys thus produced may be rolled into sheets or strips whose surface can be brought to an attractive condition by polishing, and which have a much higher tensile strength than sheets or strips rolled from zinc or known zinc base alloys. At the same time the natural advantages of the zinc, and particularly its ductility,

are not reduced, in any event to any appreciable or substantial extent, except when the proportion 39 of the third metal is over part in which cas some loss ofductility occurs.

The zinc used in the production of the alloys may be'either a high grade zinc, such as electrolytic zinc, or, the lower'grades of commercial evena small trace of aluminum causes the alloys,

45 after rolling, to develop cracks and to disintegrate. For practical purposes we prefer to use a grade of spelter known in the trade as Intermediate", whose maximum iron content is .03%, maximum lead content, 20% and maximum cadmium con- 50 tent .50 but not more than a total of 50% of all such metals and whichis substantially free from aluminum and magnesium.

We may, however, use to advantage the grade of spelter known as Brass special. (maximum impurities, iron .03%, lead .60%, cadmium 50%, total not over 1.00%, or the grade known as High grade (maximum impurities, iron .03%, lead .07 cadmium .0'I%, total not over-110%). For specifications of these three grades of commercial zinc as laid down by the American Society for Testing Materials, see Metal Statistics 1930", Page 413.

When commercial zinc whichcontains no a preciable amount of cadmium or iron, especially electrolytic grade, is used, weprefer to add a small quantity of either or both of these elements for the purposeof increasing the hardness and tensile strength.

The exact proportion of copper and of the third metal will depend upon theparticular qualities of the alloys to be produced and also upon the various conditions of the process, for instance, rolling, to which the alloys are to be subjected. The particular proportions may easily be adjusted by simple experiment until the correct proportions suitable for the desired alloys are determined.

Example v 2 pounds of electrolytic grade of commercial zinc (99.99% 'zinc) were melted in an electrically heated crucible, then 14 grains of copper and 140 grains of a copper-chromium alloy containing 14 grains of chromium and 126 grains of copper were added and thoroughly mixed with the molten zinc. The molten alloy was cast into slabs and cross rolled to .050" thickness as in the rolling of commercial sheet zinc. The assay and physical properties of therolled alloy compared with commercial zinc rolled in the same way to like gauge were as given in the table below under the column marked chromium and electrolytic zinc respectively.

Table Eleetrolytic zinc Chromium alloy None None None None Trace None None 99.99

1. 00 None None 10 Trace None .None Balance Attention is called to the fact that these physical tests are significant only when compared with ordinary zinc rolled under identical conditions.

If more than 2 parts of copper are used or more than parts of the third metal, the advantages of our alloy begin to diminish. We are at present of the opinion that the copper and third metal are, when used within the limits herein specified,- held in solid solution by the zinc grains or produce compounds with one another or with the zinc itself which are in turn held in solid solution by the zinc grain. The copper and the third metal 60 should not, for best results, be used in so large an amount as would result in the production oi a secondary crystalline structure in the alloys, thus destroying their homogeneity and rendering them brittle. It is, however, to be understood that the temperature conditions under which the alloys are cast or mechanically worked may influence the degree of solubility of these metals in the zinc grain.

So far as we know, no alloys of zinc, copper and chromium in the proportions specified have ever been used commercially for producing articles by mechanically working, for instance, by extrusion, by spinning, by drawing, by forging or by rolling into sheets or strips, for all of which purposes our alloys are specially suitable. We therefore claim as novel a mechanically worked zinc prod uct made of our alloys.

Having described the invention, what we claim as new and desire to secure 'by Letters Patent 0! the United States is:

1. As a composition of matter, a homogeneous alloy having substantially greater hardness than zinc and approximately the same ductility, said alloy being capable of being rolled, stamped, and

deep drawn, and composed of from 97.1% to 99.8% of zinc, .09% to 2.18% of copper, and from .09% to 372% of chromium.

l 2. A zinc base alloy highly resistant to corrosion and of greater hardness and greater ductility than pure zinc and capable of being rolled, stamped, and deep drawn, which is comprised of substantially 1% copper, .l0% chromium, and the 5 remainder zinc.

' LELAND E. WEMPLE.

JOHN R. DAESEN. 

